Sensor wafers are used to perform process characterizations of a tool. A sensor wafer may measure many different parameters of the process, such as, but not limited to, substrate temperature profiles, and report those back to an engineer. Originally sensor wafers were used as a tool for research and development. The information provided to the engineer enabled him to refine or improve a processing step. However, with tighter tolerances and increased demands on product yield, sensor wafers have also become a valuable process monitoring tool.
A sensor wafer may be deployed to help identify problems in a processing step when the processing step begins to produce results that exceed predetermined tolerances. Currently, the use of a sensor wafer requires a substantial downtime for the tool being characterized. In order to deploy a sensor wafer in a production setting, a technician must first take the tool offline. Then he must get a cart in order to carry the front opening unified pod (FOUP) housing the sensor wafer. After manually delivering the FOUP to the tool, the sensor wafer must be processed under the desired conditions. Thereafter, the technician must download the data logged by the sensor wafer to a laptop. The technician then needs to reassign the tool back into production. This process may take approximately 3-4 hours under ideal conditions.
Consequently, sensor wafers are typically only utilized when a processing step begins to produce devices that exceed specified tolerances. However, it would be useful to minimize the time a tool is taken off-line in order to allow for process analyses before a process begins producing devices that exceed the specified tolerances. It is within this context that embodiments of the present invention arise.